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Published on: March 9, 2017
Phosphorescent iridium(III)-bis-N-heterocyclic carbene complexes as mitochondria-targeted theranostic and
Yi Li1, Cai-Ping Tan1, Wei Zhang1
1MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, PR China.
Abstract:
Mitochondria-targeted compounds represent a promising approach to target tumors selectively and overcome resistance to current anticancer therapies. In this work, three cyclometalated iridium(III) complexes (1-3) containing bis-N-heterocyclic carbene (NHC) ligands have been explored as theranostic and photodynamic agents targeting mitochondria. These complexes display rich photophysical properties, which greatly facilitates the study of their intracellular fate. All three complexes are more cytotoxic than cisplatin against the cancer cells screened. 1-3 can penetrate into human cervical carcinoma (HeLa) cells quickly and efficiently, and they can carry out theranostic functions by simultaneously inducing and monitoring the morphological changes in mitochondria. Mechanism studies show that these complexes exert their anticancer efficacy by initiating a cascade of events related to mitochondrial dysfunction. Additionally, they display up to 3 orders of magnitude higher cytotoxicity upon irradiation at 365 nm, which is so far the highest photocytotoxic responses reported for iridium complexes.
Insights
Mitochondria-targeting iridium complexes show potent anticancer activity, acting as theranostic agents. These compounds offer enhanced photodynamic therapy, significantly improving cancer treatment outcomes.
Area of Science:
- Inorganic Chemistry
- Medicinal Chemistry
- Photochemistry
Background:
- Mitochondria-targeted compounds are crucial for selective tumor targeting and overcoming drug resistance in cancer therapy.
- Cyclometalated iridium(III) complexes offer unique photophysical properties for theranostic and photodynamic applications.
Purpose of the Study:
- To explore novel bis-N-heterocyclic carbene (NHC) iridium(III) complexes as mitochondria-targeting agents for cancer treatment.
- To evaluate their potential as theranostic and photodynamic agents with enhanced photocytotoxic responses.
Main Methods:
- Synthesis and characterization of three cyclometalated iridium(III) complexes with NHC ligands.
- Assessment of cytotoxicity against cancer cell lines and comparison with cisplatin.
- Investigation of intracellular uptake, localization, and theranostic capabilities using live-cell imaging.
- Mechanistic studies on mitochondrial dysfunction and phototoxicity upon UV irradiation.
Main Results:
- The synthesized iridium(III) complexes (1-3) exhibit strong cytotoxicity, surpassing that of cisplatin.
- Complexes efficiently penetrate cancer cells (HeLa) and induce/monitor mitochondrial morphological changes for theranostic effects.
- Anticancer efficacy is linked to the induction of mitochondrial dysfunction.
- A significant increase (up to 3 orders of magnitude) in cytotoxicity was observed upon 365 nm irradiation, representing a record for iridium complexes.
Conclusions:
- Bis-NHC iridium(III) complexes are effective mitochondria-targeting agents with dual theranostic and photodynamic anticancer capabilities.
- These complexes demonstrate superior efficacy compared to cisplatin and exhibit remarkable photocytotoxicity, paving the way for advanced cancer therapies.
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